/*********************************************************************
 * Copyright (C) 2003 Andrew Khan
 * <p>
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 * <p>
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 * <p>
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 ***************************************************************************/

package jxl.biff.drawing;

import jxl.biff.IntegerHelper;

/**
 * The Drawing Group
 */
class Dg extends EscherAtom {
    /**
     * The data
     */
    private byte[] data;

    /**
     * The id of this drawing
     */
    private int drawingId;

    /**
     * The number of shapes
     */
    private int shapeCount;

    /**
     * The seed for drawing ids
     */
    private int seed;

    /**
     * Constructor invoked when reading in an escher stream
     *
     * @param erd the escher record
     */
    public Dg(EscherRecordData erd) {
        super(erd);
        drawingId = getInstance();

        byte[] bytes = getBytes();
        shapeCount = IntegerHelper.getInt(bytes[0], bytes[1], bytes[2], bytes[3]);
        seed = IntegerHelper.getInt(bytes[4], bytes[5], bytes[6], bytes[7]);
    }

    /**
     * Constructor invoked when writing out an escher stream
     *
     * @param numDrawings the number of drawings
     */
    public Dg(int numDrawings) {
        super(EscherRecordType.DG);
        drawingId = 1;
        shapeCount = numDrawings + 1;
        seed = 1024 + shapeCount + 1;
        setInstance(drawingId);
    }

    /**
     * Gets the drawing id
     *
     * @return the drawing id
     */
    public int getDrawingId() {
        return drawingId;
    }

    /**
     * Gets the shape count
     *
     * @return the shape count
     */
    int getShapeCount() {
        return shapeCount;
    }

    /**
     * Used to generate the drawing data
     *
     * @return the data
     */
    byte[] getData() {
        data = new byte[8];
        IntegerHelper.getFourBytes(shapeCount, data, 0);
        IntegerHelper.getFourBytes(seed, data, 4);

        return setHeaderData(data);
    }
}
